The UN now estimates that there will be 9.6 billion people by 2050, which is a revision upwards from their 2010 estimate of 9.3 billion. For some environmentalists, this is a scary thought. A simplistic take on natural resource use suggests that more people mean more consumption and more pollution.
Estimating global population, let alone projecting population two generations from now, is a tricky business. While some groups estimated that the world passed seven billion people on October 31, 2011, others thought that the milestone was passed in March of 2012. Even the world’s best censuses have a 1-2 percent margin of error.
The 2050 projections have been revised upwards because of changing demographic trends in the developing world. Projections assume that global fertility rates will converge to 2.1 children per woman and a stable population. However, fertility rates have remained higher than projected in many countries, particularly in sub-Saharan Africa. Below is a chart showing the countries with the largest upward projections (as a percentage of their population).
Accurately predicting population decades from now is difficult, but the multiple upward revisions in recent years make for a worrying trend. While growth in some countries is more or less reflecting demographers’ predictions, population growth in other countries continues to spiral upwards. Nigeria, which doesn’t even make the above chart, has had its 2050 projections revised from 289 million in 2008 to 390 million in 2010 to 440 million this year. What will the next projection be?
Most of this growth is happening in developing countries, as fertility rates have mostly stabilized in the developed world.
As a Peace Corps volunteer in Morocco, I worked on family planning projects. Many of the women with whom I spoke struggled to access birth control on a consistent basis. What’s more, doctors often did not take the time to explain how to use birth control. One woman with whom my colleague spoke asked why the birth control pill her husband was taking wasn’t keeping her from getting pregnant.
While use of contraceptives has increased, access to birth control remains a huge barrier in many parts of the world. The United Nations Population Fund estimates that 215 million women want to delay or cease childbearing – about one in six women of reproductive age – but do not have the means to use birth control. Helping these women would be a huge win not only for them, but also for the environment.
Slowing population growth could reduce greenhouse gas emissions by as much as 1.1 billion tons per year by 2050. Family planning is an inexpensive way to reduce greenhouse gas emissions. Climate scientists normally talk about the “abatement cost” of a particular technology or behavior change, i.e. how much each ton of greenhouse gas reduced will cost. For instance, the abatement cost of solar PV was estimated at around $15-20 per ton of CO2 by McKinsey in 2009. Tom Lovejoy estimates that the abatement cost of reducing carbon emissions through family planning is $4.50 per ton. If carbon pollution is all you care about, reducing population growth through family planning is cheaper than reducing per capita greenhouse gas emissions (although both are needed).
It’s important to note, however, that despite increasing populations in developing countries, these countries are largely not responsible for historical or future greenhouse gas emissions. The United States, China, and the European Union all have relatively stable populations, but are responsible for most of global emissions. The USA’s per capita emissions was around 17.2 tons per year in 2009, while Nigeria’s was 0.6 tons per year.
Of course, impact on climate isn’t the only environmental consequence of a growing world population. The areas with the highest rates of population growth also tend to have the greatest pressures on local natural resources. Sub-Saharan Africa and South Asia are already facing challenges from water scarcity and deforestation with their existing populations. What’s more, much of this growth is happening in urban areas where infrastructure is overwhelmed by the growth explosion. Slums and urban poverty are the result.
Support for family planning and educating women – which is associated with lower fertility rates – has benefits for local populations and the earth. Giving women the tools and knowledge they need is an important goal that I think is often overlooked by many environmentalists.